This invention relates to a data processing unit diagnosis control apparatus, and more particularly a diagnosis control apparatus utilizing a microprocessor for loosely controlling a diagnosis.
There are data processing apparatus which require initial setting when they are started. For example, in a microprogram control type data processing apparatus with control memory constituted by a volatile random access memory (RAM), at the time of starting the apparatus, it is necessary to load in the control memory a microprogram stored in a nonvolatile information preserving means such as a ROM or a floppy disk. Among flip-flop circuits which hold information, there are some flip-flop circuits which are required to be set with predetermined values at the time of starting the apparatus depending upon the construction thereof. Such operation is termed an initial setting operation.
During the operation of the data processing apparatus, for the convenience of operation, there may be displayed the internal conditions of the apparatus, for example the state of a clock pulse, presence or absence of a malfunction, the state of loading and the contents of specific flip-flop circuits and registers. Such an operation is called a state display operation.
When the data processing apparatus becomes faulty, according to an instruction of the operator and a preprogrammed procedure, various operations are performed such as applying the clock pulse, reading out data stored in registers and memory devices, and reading out of data from a tracer contained in the apparatus. Such an operation is called diagnostic maintenance operation.
The initial setting operation, the state display operation and the diagnostic maintenance operation are generally termed a diagnosis control operation. In the prior art a portion or all of the diagnosis control operation has been exerted according to a preprogrammed procedure by using a processor contained in the data processing apparatus which is the object of the diagnosis control.
For example, U.S. Pat. No. 4,308,615 entitled "Microprocessor Based Maintenance System" discloses an example of the diagnostic maintenance system in which setting and display operations closely relating to the logical state of the data processing apparatus to be diagnosed are executed by the microprocessor instead of an operator according to a procedure based on the object of the diagnosis. The microprocessor is connected with the data processing apparatus to be diagnosed through an interface exclusively provided for the data processing apparatus, and directly controls the functional parts for diagnostic maintenance which are closely relating to the logical state of the data processing apparatus, by means of an I/O operation of the microprocessor.
With this system, however, since the apparatus to be diagnosed and the processor for controlling the diagnosis are closely related in terms of hardware, i.e., various registers, there is a defect that the load of the processor is large because the processor must handle a number of input/output operations of the various registers. Especially when the processor is used for controlling an interface between the operator and the apparaus, which is an object other than the control of the apparatus to be diagnosed, a response characteristic of the system is degraded due to the large load of the processor, or the construction of the program becomes complicated if the high response characteristic is to be maintained.